Re: [PATCH 32/34] xen/io: use __smp_XXX barriers

2016-01-04 Thread Stefano Stabellini
On Wed, 30 Dec 2015, Michael S. Tsirkin wrote: > include/xen/interface/io/ring.h uses > full memory barriers to communicate with the other side. > > For guests compiled with CONFIG_SMP, smp_wmb and smp_mb > would be sufficient, so mb() and wmb() here are only needed if > a non-SMP guest runs on

[PATCH 32/34] xen/io: use __smp_XXX barriers

2015-12-30 Thread Michael S. Tsirkin
include/xen/interface/io/ring.h uses full memory barriers to communicate with the other side. For guests compiled with CONFIG_SMP, smp_wmb and smp_mb would be sufficient, so mb() and wmb() here are only needed if a non-SMP guest runs on an SMP host. Switch to __smp_XXX barriers which serve this